Lapping machine



H. S. INDGE LAPP ING MACHINE Jan. 19, 1943.

Filed July 4, 1942 3 Shee S-Sheet l :hvumvfoc HEHEERTE [ND 55' ilkiomw/q Jan. 19, 1943. H. s. lNDGE LAPPING MACHINE Filed July 4, 1942 5 Sheets-Sheet 3 5%. mm E.

Patented Jan. 19,

LAPPING moms Herbert S. Indge, Westboro. Masa, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application July 4, 1942, Serial No. 449,715

Claims.

The invention relates to lapping machines, and more particularly to a lapping machine having an automatic work loading mechanism.

One object of the invention is to provide a simple and thoroughly practical lapping machine for producing fine finishes on either fiat or cylindrical work pieces between two opposed relatively rotatable lapping elements. A further object of the invention. is to provide a lapping machine having a pair of opposed relatively rotatable lapping elements which are relatively revolved to produce a combined rotary and planetary movement of the lapping elements relative to a work piece.

Another object of the invention is to provide a multiple work cage which is arranged to be automatically indexed to and from loading positions. A further object of the invention is to provide a lapping machine of the opposed wheel type in which a work cage for supporting a plurality of pieces of work to be lapped is moved automatically into an operative position between the lapping elements.

Another object of the invention is to provide a lapping machine with an electrically operated control whereby a work cage having a plurality of work pieces to be lapped is automatically moved or indexed into an operative position between the lapping elements, after which the lapping operation proceeds for a predetermined time interval as governed by an electrically operated control. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. l is a fragmentary front elevation of a lapping machine embodying this invention, having parts broken away and shown in section, to gether with a hydraulic piping and wiring diagram of the controland actuating mechanisms therefor;

Fig. 2 is a vertical sectional view, taken approximately on the line 2--2 of Fig. 1;

Fig. 3 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line -3-3 of Fig. 2; and

Fig. 4 is a fragmentary sectional view, on an enlarged scale, of the reversing switch for controlling the cage positioning mechanism.

The improved lapping machine, as disclosed in I the drawings, comprises a base It which supports a pair of opposed spaced lapping wheels II and I2 having opposed plane lapping surfaces arranged simultaneously to engage opposite sides of a work piece to lap the same. The lapping element II is mounted at the lower end of a vertically arranged rotatable spindle l3 which is rotatably journalled eccentrically within a rotatable sleeve M. The spindle l3 and sleeve ll are each provided with independent driving mechanisms so that the lapping wheel I I may be rotated about the ems of the wheel spindle I 3 and the sleeve It may be rotated about its axis of rotation to produce a combined rotary and planetary movement of the lapping wheel I I.

Similarly, the lower lapping wheel I2 is supported on the upper end of a rotatable spindle l5 which is rotatably and eccentrically ioumalled within a rotatable sleeve It. The spindle l5 and the sleeve it are each arranged to be independently rotated so as to rotate the lapping wheel l2 about the axis of its supporting spindle i5 and to rotate the sleeve it about its axis of rotation so as to produce a combined rotary and planetary movement of the lapping wheel l2.

A driving mechanism is provided for rotating and revolving the lapping wheels Ii and I2. A variable speed electric motor 2o is mounted within the base In of the machine. A pulley 2| is mounted on the end of the motor drive shaft and is connected by means of a driving belt 22 with a pulley 23 which is mounted on the outer end of a rotatable shaft 24. The shaft 24 is Journalled in a bearing 25 fixedly supported in the base III of the machine. A bevel gear 28 is mounted on the inner end of the shaft 24 and meshes with a bevel gear 21 whichis in turn keyed to a vertically arranged rotatable shaft 28. The shaft 28 is Journalled in bearings 28, 30 and 3| which are fixedly mounted within the base iii of the machine.

The lower end of the shaft 28 is provided with a pulley which is connected'by means ofa driving belt 38 with a larger diameter pulley 31. The pulley 31 is removably mounted on the lower end of the spindle I5 so as to rotate the lower lapping wheel l2. An idler pulley 38 is rotatably mounted on a stud 39 which is in turn supported by an idler bracket 40 to take up the slack and to properly tension the driving belt 36. The pulleys 35 and 31 may be readily changed to facilitate rotating the lapping element or wheel I2 at a desired speed.

The upper lapping element II is similarly rotated either in the same or in the opposite direction from the lower lappingv wheel I2. As illustrated in Fig. 2, a driving mechanism has been shown for rotating the lapping wheel spindle I3 and the lapping wheel II in the opposite direction from the lapping wheel I2. A gear 45 is keyed on the shaft 28 and meshes with a gear 46 which is keyed to a rotatable shaft 41. The shaft 41 is joumalled in a bearing 48 in the base I0. A pulley 49 is removably keyed to the upper end of the shaft 41 and is connected by means of a driving belt 50 with a pulley 5I which is removably mounted on the upper end of the .lapping wheel spindle I3 to rotate the spindle I3 and the upper lapping wheel II in a direction opposite to the rotation of the lower lapping wheel I2. An idler pulley 52 is rotatably.sup'- ported on a shaft 53. The shaft 53 is supported by idler brackets 54 and 55 which are rotatably supported on the shaft 28.

If it is desired to rotate the spindle I3 and lapping wheel II in the same direction as the spindle I5 and lapping wheel I2, the pulley 49 may be removed from the shaft 41 and mounted on the upper end of the shaft 28 so as to drive the spindle I3 in the same direction as the spindle I5.

In order to secure the desired and predetermined lapping action, it is desirable -to impart a planetary motion to the lapping wheels I I and I2. This planetary movement is obtained by independently rotating the sleeves I4 and I6 about their respective axes. The vertical drive shaft 28 is provided with a driving gear 60 which is slidably keyed thereto and is held in adjusted position thereon by means of a set screw. The gear 60 meshes with a gear 6| which is rotatably supported on a stud 62. The gear 6I meshes with a gear 64 which, as illustrated, is formed by cutting elongated gear teeth formed in the periphery of the sleeve I4. The gear 64 is a wide faced gear having relatively long gear teeth to facilitate longitudinal or axial movement of the quill or sleeve I4 during movement of the upper lapping wheel II to and from an operative position. When the shaft 28 is rotated, it serves not only to transmit rotary motion through the belt 50 and pulley 5| to rotate the spindle I3 but also through the gears 60, 6I and 64 to rotate the sleeve I4 to impart a planetary or revolving movement to the lapping wheel II during rotation thereof.

Similarly, a gear 65 is mounted on the drive shaft 28. The gear 65 meshes with a gear 66 which is supported on a rotatable shaft 61. The shaft 61 is journalled in bearings 68 and 69 supported by the base I0. The gear 66 meshes with a gear I formed on the periphery of the sleeve I6. It will be readily apparent from the foregoing disclosure that when the shaft 28 is rotated, a rotary motion is transmitted by the belt 36 and pulley 31 to rotate the spindle I and the lower lapping wheel I2 about the axis of the spindle I5, and at the same time the gears 65, 66 and I0 serve to rotate the sleeve I6 so as to impart a planetary or revolving motion to the lapping wheel spindle I5and the lapping wheel I2 during rotation thereof.

A fluid pressure system is provided for moving the lapping wheels II and I2 relatively toward and from each other. In the preferred form the upper lapping wheel is moved toward and from the lower lapping wheel I2 by means of a pair of diametrically opr )sed fluid pressure cylinders and BI .which are in turn fixedly mounted on the frame 82 which is fixed relative to the base I0. The cylinders 80 and 8| are provided with pistons 83 and 84, respectively. The pistons 83 and 84 are connected by piston rods 85 and 86 with a flanged plate 81 which is rotatably supported by a groove 88 formed in the lower end of the sleeve I4. The piston rods 05 and 86 are fixedly connected to the flanged plate by means of a plurality of nuts so that when the pistons 83 and 84 are moved within the cylinders 80 and 8|, the piston rods 85 and 86 will cause a corresponding movement to be transmitted to the vertically movable sleeve I4, the spindle I3, and the lapping wheel II.

Fluid for a fluid pressure system is supplied from a reservoir 90 formed as a box-like section within the base I0. Fluid is conveyed from the reservoir 90, through a pipe 9I, by means of a motor driven fluid pump 92 which forces fluid under pressure through a pipe 93 to a reversing or control valve 94. The valve 94 is a balanced piston type valve comprising a valve stem 95 having formed integrally therewith a plurality of valve pistons 96, 91 and 98. A variable pressure relief valve 99 is connected with the pipe 93 and serves to maintain the desired operating pressure in the system. If the pressure within the hydraulic system becomes excessive, the pressure relief valve 99 opens and by-passes excess fiuid under pressure through a pipe I00 into the reservoir 90.

Fluid under pressure from the pump 92 passing through the pipe 93 enters a valve chamber IOI located between the valve pistons 91 and 98 and, in the position of the valve shown in Fig. 1, passes outwardly through a pipe I02 into cylinder chambers I03 and I04 to cause a downward movement of the pistons 83 and 84 to move the upper lapping wheel II downwardly and serves to maintain the lapping wheel II in lapping engagement with the work pieces to be lapped during the lapping operation. During the downward movement of the pistons 83 and 84, fluid is exhausted from cylinder chambers I06 and I01, through a pipe I08, into a valve chamber I09 located between the valve pistons 96 and 91, and out through an exhaust pipe IIO into the reservoir 90.

A manually operable control lever II I is provided for actuating the valve stem 95. The lever III is fixedly mounted on a rock shaft II2. A short arm or lever H3 is also fixedly connected I with the shaft H2 and is connected at its other end with the valve stem 95. The valve stem 95 may be moved in either direction by means of the manually operable lever III to cause an upward or downward movement of the upper lapping wheel II. In the preferred construction, a pull type electric solenoid H4 is operatively connected to the upper end of the valve stem 95 and is arranged so that when the solenoid H4 is energized, the valve stem 95 will be moved upwardly into the reverse position from that shown in Fig. 1. When the valve 94 is shifted into its uppermost position either by manual actuation.

of the lever I II or by energization of the solenoid I I4, 'fiuid under pressure passing through the pipe 93 enters the valve chamber I09 located between the valve pistons 96 and 91 and passes through the pipe I08 into the cylinder chambers I06 and 'asoeme an inoperative position. During the upward movement of the lapping wheel II, fluid within the cylinder chambers I03 I and I04 exhausts through the pipe I02, through the valve chamber IN, and out through the pipe IIO into the reservoir 30.

In order to obtain a maximum production from the improved lapping machine, a multiple work cage is provided comprising work cages. I I5 and H6 each of which is rotatably supported by a longitudinally movable work table H1. The work cages II 5 and H6 are disk-shaped members having a plurality of work receiving apertures simultaneously to support a plurality of work pieces II8 for a lapping operation. As shown in Fig. 1, the cage supporting table H1 is supported by a plurality of pairs of anti-friction rollers H9,- I20 and I2I (Figs. 1 and 2) which ride within a groove I22 formed adjacent to the front edge of the machine and a correspondingly arranged set of rollers II8a, I200 and I2la having V-shaped peripheries (Figs. 2 and 3) which ride within a V-way I23 formed on the base I and which is arranged parallel to the grooved flat way I22.

As illustrated in Fig. 1, the work carrying cage H is in a loading position and the cage H6 is in an operative position between the lapping wheels II and I2. After the lapping operation has been completed on the work pieces supported in the cage II8, the upper lapping wheel II is raised and the table I1 indexed or moved toward the right into position II1a (Fig. 1) which moves the cage II6 toward the right to an inoperative or loading position II6a. and at the same time shifts the cage II5 toward the right into an operative position between the lapping wheels II and I2.

A fluid pressure mechanism is provided for indexing the cage supporting table II1, com prising a fluid pressure cylinder I25 which is fixedly supported on the under side of the table II by brackets I26 and I21. Spaced pistons I28 and I29 are slidably mounted within the cylinder I25 and are connected by hollow piston rods I30 and I3I, respectively, with hollow brackets I32 and I33, respectively. The brackets I32 and I33 are fixedly mounted on opposite ends of the base III. A fluid pressure reversing or control valve I35 is provided for controlling the admission of fluid under pressure to-opposlte ends of the cylinder I25. The valve I35 is a piston type reversing valve comprising a valve stem I36 having formed integrally therewith a plurality of valve pistons I31, I38 and I39. A pipe I46 is connected between the bracket I32 and the valve I35, and a pipe I4I is connected between the bracket I33 and the valve I35.

In the position of the valve I35 (Fig. 1).

- fiuid under pressure passing through the pipe 83 passes through apipe I42 into a valve chamber I43 located between the valve pistons I38 and I39 and passes out through the pipe I40, through the hollow ,bracket I32, through the hollow piston rod I30, into a cylinder chamber at the left-hand end of the cylinder I25, to cause the cylinder I25 and table III to move to the extreme left-hand position, such as shown in Fig. 1. During the movement of the table II1 toward the left, fluid is exhausted from a cylinder chamber located at the right-hand end of the cylinder I25, through the hollow piston rod I3I, through the hollow bracket I33, through the pipe I4I, through a valve chamber I44, and out through a pipe I45 which exhausts into the pipe I46, into the cylinder chamber I44, and

through the pipe I, the hollow bracket I33, the hollow piston rod I3I, into the right-hand. end cylinder chamber in cylinder I to cause the table II1 to move toward the right into position II1a (Fig. 1).

In order to shift the valve stem I38 automatically, an electric solenoid I41 is operatively connected to the left-hand end of the valve stem I36 and is arranged when energized t move the valve stem I36,to its extreme left-hand end position. Similarly, an electric solenoid I48 is operatively connected to the right-hand end of the valve stem I36 and serves when energized to cause the valve stem I36 to move into, the position illustrated in Fig. 1.

In order to support the work pieces II8 when they are placed within the apertures of the work cage II5, a supporting plate I 50 (Fig. 3) is proof brackets I54 and I56 to serve as a support for work pieces when loaded into the cage II8 when it is in a loading position I I60, at the righthandend of its stroke (Fig. 3). In order that the work pieces may readily slide with the cages H5 and H6 from the supporting plates I and I53, respectively, onto the operative face of the lower lapping wheel I2, a plate I56 is provided which has a central aperture I51 which is slightly larger than the outer diameter of the lower lapping wheel I2. The plate I56 is provided with a stud I58 (Fig. 3) which rides in an elongated slot I53 formed in the plate I50 so that the plate I56 is free to move in a longitudinal direction but cannot rotate. The plate I56 is further provided with a plurality of downwardly extending studs I60 and I6I (only two of which have been shown) having rollers .162 and I63 rotatably supported at their lower ends. The rollers I62 and I63 are arranged so that their peripheries engage a peripheral surface I64 on the mounting plate for the lower lapping wheel I2. The

rollers I62 and I63 riding upon the peripheral II5 may be readily moved longitudinally by movement of the table II1 to position the cage H5 and work 'pieces H8 in an operative position between the lapping wheels II and I2 A reversing switch I10 is providedhaving its casing fixedly mounted on the base I0. The switch I10 comprises an actuating stud I H which is slidably mounted within the switch casing. The plunger III is provided with a pair of V- grooves I12 and I13. An arrow-pointed, springpressed plunger I14 is carried by the switch casing to hold the plunger I1I either in the lefthand end position so as to close a circuit between the wires or conduits I15 and I16 or in a righthand end position to close a circuit between the wires or conduits I11 and I18. A pair of adjustably mounted table dogs I19 and I are supported by a T-slot I8I formed on the front edge of the table H1. The dogs I19 and I80 are arranged to engage the opposite end surfaces I82 and I 83 of the switch actuating plunger III to reverse the switch at the ends of the stroke of the table or carriage III. The electric reversing switch I10 is operatively connected in a manner to be hereinafter described to close the respective circuits to energize the solenoids I41 and I48. The end faces I84 and I85 of the casing of the reversing switch I10 serve in cooperation with the table dogs I19 and I80 positively to limit the longitudinal movement of the table I I1 precisely to locate the work cages H5 and I I6 in operative positions between the lapping wheels II and I2. The rotatable sleeve I4 is rotatably supported in a vertically movable sleeve I90 which is slidably supported in a cylindrical bore I9I formed in the frame 82 which, as illustrated, is formed integral with the base I0 of the machine. The sleeve I90 is provided with a block I83 which serves as a support for a pair of adjustably mounted screws I94 and I95. The screw I94 is arranged in the path of the actuating roller of a normally open limit switch I96. Similarly, the screw I95 is arranged in the path of the actuating roller of a normally open limit switch I91.

With the parts in the position shown in Fig. 1, when the upper lapping wheel I I moves upwardly to an inoperative position, the screw I94 engages the actuating roller and closes the limit switch I96 which is connected in series with the reversing switch I10 and the solenoid I41 to energize the solenoid I41 and thereby to shift the reversing valve stem I36 toward the left into the reverse position.

Similarly, the screw I95 is arranged on the downward movement of the upper lapping wheel II to engage the actuating roller of the limit switch I91 which operates to set an electrical time delay relay 200 in motion. The electric time relay 200 may be any standard time relay but in the preferred form may be a time delay relay known as the Microflex" manufactured by the Eagle Signal Corporation of Moline, Illinois. The

sition illustrated in Fig. 1, that is, with the lapping wheels operatively engaging work pieces supported in the lapping cage I I6, the lapping operation proceeds until the lapse of a predetermined time interval as governed by the time relay 200. After the time interval has elapsed, the time relay 200 serves through the magnetic starter switch 20I to break the circuit and thus stop the motor 20 to stop the rotation and planetary movement of the lapping wheels I I and I2. After the lapping wheels have stopped, the time relay operates ough the relay 200 to energize the magnet of the relay 204 to close a circuit so as to energize the solenoid II4 which shifts the valve stem 85 into an uppermost position so that fluid under pressure from the pump 92 passing through the pipe 93 enters the valve chamber I09 and passes through the pipe I08 to the cylinder chambers I 06 and I01 to cause an upward movement of the gear pistons 83 and 84, respectively. This movement causes an upward movement of the lapping wheel I I to move it to an inoperative position.

When the upper lapping wheel II approaches its uppermost position, the screw I94 engages the actuating roller of the limit switch I96 to close the switch to energize the solenoid I41 which serves to shift the reversing valve I 36 into an extreme left-hand end position. In this position of the valve I35, fluid under pressure from the pump 92 passing through the pipe 93 passes through the pipe I46, the valve chamber I44, the pipe I 4|, the hollow bracket I 33, and the hollow piston rod I3 I into the cylinder chamber at the right-hand end of the cylinder I25 to cause the cylinder I25 together with the table I I1 to move toward the right into position I I1a (Fig. 1). Themovement of the table I I1 toward the right continues until the dog I19 engages the stop face or abutment I84 formed on the casing of the limit switch I10 which stops the table I I1 in position I I1a with the work carrying cage II5 located in an operative position between the lapping wheels II and I2. In this poclosing of the limit switch I 90 serves through the time delay relay 200 to actuate a magnetic starter switch 20I to start the main driving motor 20 as the upper lapping wheel moves into engagement with the work pieces II8. A push button start and stop switch 202 is provided between the magnetic starter switch 20I and the source of power illustrated by the power lines 203. A relay switch 204 is connected between the power lines 203, the

' solenoid H4, and the time delay relay 200 and is arranged so that after a predetermined time interval has elapsed, as governed by the time relay 200, it will close a circuit to energize the solenoid I I4 to shift the valve stem 95 upwardly and thus admit fluid under pressure to raise the upper lapping wheel II. The time relay 200 is also operatively connected so that after a predetermined time interval and before the relay 204 is energized to energize the solenoid II4, the magnetic starter switch 20I is actuated to stop the main drive motor'20, after which the relay switch 204 energizes the solenoid I I4 to shift the valve 94 so as to cause an upward movement of the upper lapping wheel I I to an inoperative position so as to facilitate removing work pieces from an operative position between the wheels to an inoperative position while moving a fresh set of work pieces into operative relation between the lapping wheels.

The operation of this improved lapping machine will be readily apparent from the foregoing disclosure. Assuming the parts to be in the position of the parts, the work carrying cage H6 is moved into position I IGa (Fig. 3), in which position the lapped work pieces I I8 may be readily removed from the cage and the cage loaded with new work pieces to be lapped.

When it is desired to initiate the next lapping operation, the manually operable lever III is moved downwardly, that is, in a counterclockwise direction to shift the valve 94 into the position illustrated in Fig. 1 so that fluid under pressure from the pump 92 is conveyed through the pipe 93 to the valve chamber I 0| and the pipe I 02 into the cylinder chambers I03 and I04, respectively, to cause a downward movement of the lapping wheel II into an operative position. As the lapping wheel II approaches anoperative position, the actuating screw I95 engages the actuating roller of the limit switch I91 to close the same. The closing of the limit switch I91 serves to close a circuit setting the time relay 200 into operation and at the same time serves to close a circuit through the magnetic starter switch 20I to start the motor 200 so as to start the rotary and planetary movement of the lapping wheels II and I 2 to produce the desired lapping operation on the work pieces I I8 for a predetermined time interval.

As above described, after the predetermined time interval has elapsed, the cycle as above described is repeated, that is, the rotation and revolution of the lapping wheels II and I 2 is first stopped, after which the control valve 95 is shifted to an uppermost position to raise the lap- As the lapping wheel approaches P11 8 wheel ll. its uppermost position, the work table H1 is set in motion to index the cage I I into the position illustrated in Fig. 1 where it may be unloaded and loaded with fresh work pieces to be lapped. The time interval between lapping operations is very short since it is merely necessary for the operator to wait until the next work cage has been indexed to an inoperative position, after which the control lever Ill may be instantly shifted to start the next operation.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove 'set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a lapping machine having a base, a pair of opposed rotatable lapping wheels, means simultaneously to rotate said lappin wheels, means relatively to move said wheels toward and from each other, a longitudinally movable table, a pair of spaced, freely rotatable work cages supported by said table, and an automatically actuated mechanism intermittently to traverse said table successively and intermittently to position said cages in an operative position between said lapping wheels.

2. In a lapping machine having a base, a pair of opposed rotatable lapping wheels, means slmultaneously to rotate said wheels, means simultaneously to revolve said wheels about an axis ofiset relative to the axis of rotation, means relatively to move said wheels toward and from each other, a longitudinally movable table between said wheels, a pair of spaced, freely rotatable work cages on said "table, and means intermittently to traverse said table successively and intermittently to-position said cages in an operative position between said lapping wheels.

3. In a lapping machine having a base, a pair of opposed rotatable lapping wheels, means simultaneously to rotate said wheels, means relatively to move said wheels toward and from each other, a longitudinally movable table between said wheels, a pair of spaced, freely rotatable work cages supported by said table, and means actuated by and in timed relation with the separating movement of said lapping wheels to traverse said table successively and intermittently to position said cages in an operative position between said lapping wheels.

4. In a lapping machine as claimed in claim 1, the combination with the parts and features therein specified, of an electric motor to. rotate said lapping wheels and a limit switch actuated by the approaching movement of said lapping wheels automatically to start said motor to rotate the lapping wheels for a lapping operation.

5. In a lapping machine in accordance with claim 1, the combination with the parts and features therein specified, of an electric motor simultaneously to rotate said lapping wheels, a limit switch actuated by the relative approaching movement of said lapping wheels to start said motor, thereby to rotate the lapping wheels, an electric time delay which is set in motion by the closing of said switch which is arranged ping operation has proceeded for a predetermined time interval.

6. In a lapping machine as claimed in claim 1, the combination with the parts and features therein specified, of a hydraulic piston and cylinder to traverse said table to index and position said work cages, a reversing valve therefor, a solenoid operatively connected to each end of said reversing valve, a table actuated reversing switch operatively connected successively to render said solenoid operative, and means including a limit switch connected in series with said reversing switch which is actuated by the separating movement of said lapping wheels automatically to index said table successively to position the work cages in an operative position between the lapping wheels.

7. In a lapping machine having a base, a pair of opposed rotatable lapping wheels, means simultaneously to rotate said lapping wheels, means relatively to move said wheels toward and from each other, a longitudinally movable table, a pair of spaced, freely rotatable work cages supported by said table, an automatically actuated mechanism intermittently to traverse said table successively and intermittently to position said cages in an operative position between said lapping wheels, means automatically to start the rotation of said lapping wheels to initiate a lapping operation, and means automatically to stop the rotation of said lapping wheels after a predetermined time interval.

8. In a lapping machine having a base, a pair of opposed rotatable lapping wheels, means including an electric motor simultaneously to rotate said wheels, means relatively to move said wheels toward and from each other, a longitudinally movable table between said wheels, a pairof spaced, freely rotatable work cages supported by said table, means actuated by and in timed relation with the separating movement of said lapping wheels to traverse said table sucautomatically to stop said motor after the lapcessively and intermittently to position said cages in an operative position between said lapping wheels, and means actuated by and in timed relation with the approaching movement of said lapping wheels automatically to start said electric motor to rotate said wheels.

9. In a lapping machine having a base, a pair of opposed rotatable lapping wheels, means including an electric motor simultaneously to rotate said wheels, means relatively to move said wheels toward and from each other, a longitudinally movable table between said wheels, a pair of spaced, freely rotatable work cages supported by said table, means actuated by and in timed relation with the separating movement of said lapping wheels to traverse said table successively and intermittently to position said cages in an operative position between said lapping wheels, means actuated by and in timed relation with the approaching movement of said lapping wheels automatically to start said electric motor to rotate said wheels, and means automatically to stop said motor and to separate said lapping wheels after a predetermined lapping operation. I

10. In a lapping machine as claimed in claim 1, the combination with the parts and features therein specified, of an electric motor simultaneously to rotate and revolve the opposed lapping wheels, a hydraulic piston and cylinder to move one of said lapping wheels toward and from the other, a control reversing valve to admit fluid under pressure to either end of said cylinder,

switch to control the duration of the lapping operation, said time relay being arranged after a predetermined time interval to stop said driving motor andto energize said solenoid and thereby move said lapping wheels to an inoperative position.

- HERBERT S. INDGE. 

